Switch.



J. F. MGELROY.

swmm.

APPLICATION FILED AUG. 8, 1903. 1,023,264. PatentedApr. 16, 1912.

3 BHBBTBBHEET 2.

J. P. MGELROY.

SWITCH.

APPLICATION 211.511 was, 1903.

1,023,264. Patented Apr. 16, 1912.

8 SHEETS-SHEET 3.

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UNITED STATES PA ENT OFFICE.

JAMES F. MOELBOY, OF ALBANY, NEW YORK, ABsIGIl'OB TO CONSOLIDATED GABHEATING COMPANY, A. COBPOBATIQN OF WEST VIRGINIA.

SWITCH.

Specification of Letters Patent.

Patented Apr. 16, 1912.

Application filed August 8, 1908. Serial No. 447,510.

To all whom it may concern:

Be it known thatI, JAMES F. MOELBOY, a citizen of the United States, anda resident of the city of Albany, State of New York, have inventedcertain new and useful Improvements in Switches, of which the followingis a full, clear, and com lete disclosure.

This invention relates to t c class of overload or cut-out switches forelectric circuits, and the object thereof is to produce'a switch whichwill break the circuit when any abnormal condition exists in thecircuit, such as a ground or short circuit, but which will not beoperated by other sudden increases in the amount of current flowing,such as when the devices operated by the current in such circuit arebeing started up, unless so described.

My improved switch is particularly adapted for circuits in which heatingelements are included, such as heatin elements for supplying heat tosteam boi ers for the generation of steam for heating purposes and asone illustration I have shown this application of the invention.

Boilers such as those just referred to are particularly adapted to theheating of railroad trains drawn by electric locomotives, and where theboiler is located on the locomotive so that the steam heating devicesalready installed in railroad cars previousl drawn by steam locomotivesmay be use This system of heating by steam generated through the actionof electric current flowing through electric heaters forms no part of mypresent invention and is merely shown to illustrate one use .for thatinvention.

As will be seen from Fig. 1 of the drawing, the heaters shown consist ofmetallic tubes adapted to carry an electric current, and located withinthe boiler tubes or flues but not contacting electrically therewith. Thesurfaces of these parts are ordinarily separated only by aboutfive-eighths of an inch of air space, and under abnormal or accidentalconditions, the current might pass from the heating tube to the metal ofthe boiler, thereby causing a short circuit or ground, it beingunderstood that the metal of the boiler is grounded because it iscarried on the metallic frame of a car or locomotive.

In overload switches of the style previously used with motors onelectric cars and mately two and one-half with such apparatus as anelectrically heated holler, the switch is intended to prevent anoverload of current in case any accident happens to the apparatus, such,for example, as aground or short-circuit. It is always desirable to opena circuit through any translating device in case a ound occurs, and suchoverload switches ave generally been arranged so that the controllingmagnet will carry the maximum current without releasing theswitch whenthe current is acting normally, but when the ground occurs the extracurrent thereby produced is supposed to operate the magnet and open thecircuit. However, when a device like an electric motor is used, whosestarting current is large compared with the ordinary normally runningcurrent, the overload switch heretofore employed must be adjusted sothat the maximum current necessary for starting or running the motorwill be carried without operating the switch, and on the other hand sothat an excessive increase of the current, due to grounding, shalloperate the switch to open it. When electric'heaters having a large heatcoefiicient are employed in the circuit, there is always a heavy rush ofthe current through the heater until the same becomes heated up and itsresistance thereby increased. An overload switch of the prior kind musttherefore be adjusted so as to carry approxitimes the normal current,and so that the rush of the current through the heating element when itis first started will not open the circuit. The overload switch whichforms the subject of my present application, is, on the contrary, sodevised as not to open with any current however large that may be sentthrough the heaters, but to open only when a ground or short-circuittakes place in some part of the apparatus and by reason of the fact thatthe ground or short-circuit establishes a condition difi'erent from thatwhich would be established by a mere increase in the total current.

For a full, clear and exact description of that one form of my inventionwhich I at present deem preferable, reference may be had to theaccompanying drawings forming a part of this application, in which-Figure 1 shows the boiler with the heating elements therein, and shownpartly in section, said boiler being electrically connected to myimproved overload switch shown in perspective; Figs. 2 and arediagrammatic views showing my improved switch connected respectivelywith a heating device or boiler and with an electric motor; Fig. 4 showsa slight modification and Fig.5 a diagram thereof.

Referring to the drawings, the numeral 1, Fig. 1, indicates the casingof a boiler; 2 the boiler tubes; 3 the heating elements therein; 4 theinsulators at the end of the tubes "for locating and holding the heatersin position; 5 the connectors for connecting the heating elements 3 inseries; and 6 and 7 indicate the leads connecting the heating elementswith the overload switch. The overload switch comprises (see Figs. 1 and4) a base 8 upon which are mounted the usual stationary contactor strips9 of the usual or suitable material, such as carbon, and the movablecontact strips 10 carried on a yoke 11. The yoke 11 is also providedwith the usual metallic connecting blades 12 which enter the flexiblecontact jaws 13, also carried by the base and electrically connectedwith the strips 9. The yoke 11 is carried on an arm 40 pivoted at 42 andcontacts with the spring 14 for forcing the arm 40 outward when theswitch is released. An elastic bufl er 144 is provided for lessening theupward blow of the arm as the switch opens and retaining it in its openposition. A projection 15 on the yoke 11 is adapted to engage a pivotedlatch or pawl 16, which carries the armature 17. Opposite the armature17 is placed the core 18 upon which are several turns of wire formingtwo coils as indicated in 19 and 20, wound in opposite directions, andincluded respectively in the leads 6 and 7 from and to the elements 3.Upon the latch 16 there may be mounted a small weight 21 for varying thesensitiveness of the overload switch. This weight may be entirelyomitted in case it is desirable that the switch shall be very sensitive.

The numeral 22 indicates the third rail or other stationary conductorfor supplying current to the apparatus, and 23 indicates the contactshoe cooperating therewith. The lead 24 terminates at the connector 25which is electrically connected with one set of the stationary contactstrips 9 and 13. Connector 26 is electrically connected with theopposite set of contact strips 9 and 13, and when the yoke 11 is inoperative position between the two sets of contact strips 9 and 13, thecircuit is closed. The connector 26 is connected with the lead 27forming one end of the coil 20 and the other end of the coil 20 isconnected with the lead 7 supplying current to the heating elements 3.The lead 6 is connected to one end of the coil 19, and the other end ofsaid coil 19 is connected with the lead 28 passing to the returnconductor, conventionally indicated as the ground 29, connector 30 beinginterposed for this purpose.

When the switch is closed the current from the third rail enters throughthe shoe 23, lead 24, one set of stationary contact elements 9 and 13,one set of movable contact elements 10 and 12, the yoke 11, the oppositeset of movable contact elements 10 and 12, the other set of stationarycontact elements-9 and 13, the connector 26, coil 20, the lead 7 theheating elements 3, the lead 6, the coil 19, the lead 28 to the return29. Since the current passes through the coils 19 and 20 in oppositedirections, they tend to neutralize each other when the normal or eventhe heavy starting current, however great it may be, is passing throughthe heaters, but should a ground take place from any of the parts beyondthe coil 20 as indicated, for example, at 54 in Fig. 5 the current inone of the coils will be increased since that coil will be in serieswith the ground and the magnetism which was before balanced, will belessened or eliminated in the other coil which has been shunted by theground and the latch operated to open the switch. This arrangementenables the switch to be opened when a ground occurs even if the groundshould not cause any increase of the total current from the third railor stationary conductor through the apparatus. It will thus be seen thatI have provided a switch which does not require an abnormally largecurrent to operate it, but operates through a division of the currentsupplied to the heating elements or motor, such as in the case of aound, the current being diverted directly oin the grounding point to theground or return conductor without passing through one of the coils ofthe switch.

In Fig. 3 the numeral 31 indicates an electrio motor which is controlledin the same manner as the heating elements in the boiler 1, shown inFigs. 1 and 2. In Figs. 2 and 3 the movable element of the switch isindicated by the numeral 32, and the stationary elements by the numerals34 and 35, the spring for operating the switch being indicated by thenumeral 36. The other parts in these figures corresponding to Fig. 1 areindicated by the same reference numerals as in Fig. 1.

As shown in Figs. 4 and 5, the neutralizer coil 19 which is shunted bythe ground, may oppose coil 20 mechanically, as well as magnetically.Thus in Fig. 4 the latch 16 is mounted on a rod 50 and normally held byspring 52 in engagement with projection 15 on yoke 11, the longitudinalplay of rod 50 being limited by collars 53, 53. The pull of coil 20 onrod 50, against the tension of spring 52 is neutralized by the contrarypull of coil 19; When, however, coil 19 is shunted by a ground in theprotected apparatus, it lets go of the rod which then responds to thepull of coil 20, which is in series with the ground, and the switch isreleased. The collar 53 serves to limit the motion of the core when theconditions are normal. The end portions 50' of said core are made ofnon-magnetic material.

While the arrangement above described is one that illustrates theprinciple of a cut out switch provided with a neutralizing coil thatnormally opposes (either magnetically or mechanically) the operatingcoil of the switch, but lets go in the event of a ground orshort-circuit in the apparatus, yet the same principle may be alsoapplied to a switch that will respond, like an ordinary cut-out to anexcess of current in the apparatus, while still retaining the qualityand characteristic above described. Thus if the coil 20 has one or moreextra turns, as shown in Fig. 3, it will have an excess of power overcoil 19 proportional to the product of the number of extra turns by theamperes of current. If, for example, there is one extra turn and thenormal or satisfactory current which is below the responding point ofthe cut-out is two hundred amperes, then the excess power will be twohundred ampere turns and the adjustment may be such that an excess ofthis amount will not cause the cutout to act. If, however, the currentexceeds this value, the switch will respond and open the current. At thesame time an accidental ground in the apparatus will short-circuit coil19 and coil 20 will then act by removal of the opposition of coil 19,instead of by excess current in its supernumerary turn or turns.

Havin thus described my invention, I do not wish to be understood asbeing limited to the exact details of construction or arrangement ofparts set forth, for various changes may be made in my invention bypersons skilled in the art without departing from the spirit and scopethereof.

What I claim and desire to secure by Letters Patent is:

1. A switch comprising a core having coils traversed by the current, thecoils exerting a force normally in opposition, said coils be ingresponsive to an excess of current and also responsive to the shuntingof the current through one of the coils to the ground.

2. In a cut-out switch, means for opening said switch comprisingcurrent-carrying devices of unequal force and responsive to an excess ofcurrent, and also responsive to the shunting of the current through oneof said devices by a ound.

3. In combination with a translating device, a cut out switch havingcoils traversed by the current passing through said device, one of saidcoils exerting a force counterbalancing a fraction of the force of theother coil and said coils being responsive to an excess of current, andalso responsive to the shunting of the current through one of the coilsby ground.

4. In combination with a translating device, a cut out switch havingunequal differential coils traversed by the current passing through'said device, said coils being responsive to an excess of current, andalso responsive to the shuntin of the current through one of saiddevices%iy a ground.

5. In a cut-out switch, differential controlling coils in series andnormally inactive upon said switch,one coil having a greater number ofturns than the other, and a translating device located in the circuitbetween said coils.

Signed at Albany, county of Albany, State of New York, on the 6th day ofAug, 1908.

JAMES F. MCELROY.

Witnesses:

BEULAH CABLE, JOHN M. ESTERLY.

